user exit in Fixed Term Deposit (Transaction TM01)

Hi,

I want block creating some production type(Eg: 101)  in transaction TM01 through user exit, because this certain production type will be migrated to  New system (Summit) on cut over day,others production type transaction will be remain on SAP system.

What i need is, If some user create transaction with production type 101 using TM01 transaction,then system will delivery message " This production type 101 is offline,Exit and not saved".  then transaction halt and exit.

but others,(Eg: 102) will continue without break.

can anyone tell me what user exit or method can achieve it? 

Appreciate any inputs - thanks.